The present invention relates generally as indicated to a radome deicer and, more particularly, to a radome deicer having inflatable/deflatable chambers for use on an aircraft antenna radome.
A radome is provided as a protective housing for antennas or other equipment which transmit and/or receive electromagnetic waves in hostile environments. In some applications, such as with a radome installed on an airplane or helicopter, the radome is highly susceptible to icing. Ice build-up on the outside surface of a radome can contribute to attenuation and distortion of the transmitted/received electromagnetic waves and thus must be removed if the equipment is to operate appropriately.
In the past, deicers have been used to remove ice accumulation on aircraft structures such as, for example, airfoils, impeller blades, and/or intake nozzles. Such aircraft deicers are generally designed to effectively remove accumulated ice without overly impacting any important flight forces (e.g. lift, drag, weight). A radome deicer must not only meet this criteria, but must also be designed to avoid adversely altering the incoming/outgoing electromagnetic waves so that transmission effectiveness is not reduced. Moreover, a radome deicer often presents other special design considerations not usually encountered with other aircraft deicers.
The present invention provides a radome deicer which removes ice accumulation without sacrificing transmission effectiveness.
More particularly, the present invention provides a radome deicer comprising a cap portion covering the active portion of a radome but unattached thereto. The cap portion can comprise an inner layer and an outer layer defining inflatable/deflatable chambers. When the chambers are deflated, the inner layer lies flat against the active portion of the radome. When the chambers are inflated, the inner layer is lifted off the active portion of the radome. The inner and outer chamber-defining layers can each be made of an non-stretchable material (e.g., square woven nylon fabric) so that the inflated chambers have a tube shape with a roughly circular cross-section. A stretchable skirt portion can be attached to the cap portion to allow the deicing cap to lift off of the active portion of the radome when the chambers are inflated.
This construction of the radome deicer allows it to be thinner than conventional pneumatic deicers. Specifically, the thickness of the cap portion is less than 0.070 inch, less than 0.060 inch, and/or about 0.050 inch. This is at least 0.020 inch thinner than a conventional deicer wherein the inner chamber-defining layer is bonded to the aircraft structure and the outer chamber-defining layer is made of an extensible material. A deicer according to the present invention having a thickness of about 0.050 inch is especially suitable for use on a radome wherein the housed radio equipment receives/transmits at higher frequencies.
The deicer of the present invention can be constructed so that an active radome portion having a complex compound-curved shape can still be covered with a square woven fabric. Specifically, the carcass of the radome deicer has a cap portion made from two non-extensible layers (which define the chambers) and a skirt portion made from an extensible layer. The non-stretchable chamber-defining layers can be formed from a plurality of panels. For example, if a dome-shaped distal portion of the radome is its active portion, roughly triangular panels can be joined together to form the cap portion of the carcass.
The carcass can be provided with a fluid-path construction that allows the use of an external air connection located remote from the radome base as is sometimes necessary if the radome is internally pressurized. Specifically, a channel is formed in the carcass by an extension tab of the non-extensible layers which is secured to the extensible layer by seams. The channel communicates with the chambers and can extend through the skirt portion whereby fluid can be introduced and evacuated to inflate and deflate the chambers.
The carcass can be constructed to prolong the fatigue life of the deicer by preventing over-stretching and cracking of a cover layer of the deicer. Specifically, the seams on the outer surface of the carcass can each comprise a stitch line, a gum coating over the stitch line, and a fabric strip over the gum coating. These seams may include chamber-defining seams, cap-skirt attachment seams, channel-forming seams, and/or chamber-closing seams.
Thus a radome deicer according to the present invention can be constructed thinner than conventional pneumatic deicers, can accommodate geometric shapes with square woven fabric, can be compatible with remote air connections, and/or can maintain an acceptable fatigue life. These and other features of the invention are fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail a certain illustrative embodiment of the invention, this embodiment being indicative of but one of the various ways in which the principles of the invention can be employed.